ItemsContentProvider.downloadMissingImages(): Use the local URI instead of the content URI.
ItemsContentProvider: Try to catch NoNetworkExceptions that could cause crashes.
ItemsContentProvider.cacheUriToFile(): Check that it's not in progress.

In theory this could happen just after adding a new subject if
downloadMissingImages tries to get it before our regular async task has managed
to get it.
HttpUtils: Specify a timeout for connections.

Otherwise they can just never return (the default), so we never know that the
connection/download has failed.
ItemsContentProvider: Unmark image downloads in progress after failure too.

Otherwise we would never try them again until after an app restart.
ItemsContentProvider: Avoid multiple simultaneous requests for objects.

Because this would just slow us down and lead to use getting items we don't need
when using a slow connection.
SubjectFragment: Ignore "next" items.

The parent ClassifyFragment will give a real item ID to its child
SubjectFragment anyway, so this would be an unnecessary simultaneous
request for a first item at first startup.
ClassifyFragment: Avoid unnecesssary repeated queries for "next".

Because that is unnecessary and slow.
About: Mention the license of the answer icons and example icons.

Because we now bundle them.
About: Change the CC license name for the app icon image.

Because eso.org seems to have changed from
Creative Commons 3.0 Unported
to
Creative Commons Attribution 4.0 International
Remove extra semicolon.
QuestionFragment: Do not use == to compare Strings.

Sometimes I forget that this is not C++.
strings.xml: Escape ' with \.
build.gradle: Update build-tools and compat versions.
1.16
Classify: Provide an icon for the Invert action.

* app/src/main/res/drawable-svg-originals/ic_action_invert.svg:
  Created in Inkscape, based on the icon used in the Galaxy Zoo web app:
  http://static.zooniverse.org/www.galaxyzoo.org/images/icons.png
* app/src/main/res/drawable-*/ic_action_invert.png:
  Created with the Android Asset Studio with the default settings
  for action icons, with the Holo Dark theme:
  http://romannurik.github.io/AndroidAssetStudio/icons-actionbar.html#source.type=image&source.space.trim=1&source.space.pad=0&name=ic_action_icon_invert&theme=dark&color=33b5e5%2C60
Action bar: Define a sequence for the action items.
DecisionTree: Make getFirstQuestion() private.

Because it is not used outside the class.
QuestionFragment: Restart: Do not change the itemID by getting "next" again.

Just wipe the classification in progress and clear the question ID
so we show the first question again.
Initial skeleton code for a SyncAdapter.

Based on
http://developer.android.com/training/sync-adapters/index.html